Thunder window isn’t wide enough

[BTCapsule]

When I send a transaction and open the Mempool Explorer, this is what it looks like:

Notice the vertical letters on the far right side. I can expand the window and see everything, but there’s still an issue with the Transaction Builder tab. This is what it looks like when I first open Thunder:

It looks like there’s no other sections, but when I expand, it looks like this:

[Ash-L2L]

Egui seems to sometimes fail to render panels if they are not within the view area.
I've added a scrollbar in #43 to make it clearer that there are more UI elements, but unfortunately they are not always visible until the window is resized, even if they should be scrolled into view.
Keeping this open, as #43 is only a partial fix

[fumin]

This PR #81 increases the aforementioned Transaction Builder tab, which should fix this.